Seepage gasoline detection

ABSTRACT

Thiophane is added to gasoline in an amount insufficient to change the odor of the gasoline, but sufficient to be detected when a sample of seepage gasoline containing the thiophane is subjected to a physical separation process, such as gas chromatography. Preferably, the amount of thiophane added to the gasoline is about 0.1 percent by volume of the fuel.

United States Patent Inventors Appl. No. Filed Patented Assignee SEEPAGE GASOLINE DETECTION 1 Claim, No Drawings US. Cl 23/230 EP, 73/40 int. Cl G0lm 3/20, GOln 33/22 Field of Search 23/230 C, 230; 7.3/23.l, 40, 40.7; 48/195 References Cited UNITED STATES PATENTS -8,027,754 4/1962 Alquist et al 73/40 X OTHER REFERENCES Olsen, A. W., Chem. Abstr. 64, 1862c (1966) .lentoft et al., Chem. Abstr. 64, 173 l2f( 1966) Ripperger, W., Chem. Abstr. 67, lO164ly (1967) Primary Examiner-Morris O. Wolk Assistant Examiner-R. M. Reese Att0meysManahan and Wright and Donald F. Wohlers ABSTRACT: Thiophane is added to gasoline in an amount insufficient to change the odor of the gasoline, but sufficient to SEEPAGE GASOLINE DETECTION v This invention relates to the incorporation of an identifying agent in liquid, hydrocarbon fuels. More particularly, it relates to a process for tracing the origin of seepage gasoline.

Massive distribution systems have been developed to supply consumers with gasoline and other liquid hydrocarbon fuels and these systems include the use of many storage receptacles in all stages of the distribution. Large tank farms, for example, are frequently found near pipeline, tanker, and barge terminals, near refineries and the like, and at service stations for storing the gasoline prior to its sale.

Such storage tanks and their associated piping, unfortunately, are often susceptible to leakage due to faulty construction or installation, corrosion, and the like.

Generally, the tanks used for storing gasoline and other liquid fuels are constructed with their bottom surface resting on the ground or are buried underground. Gasoline or other liquid leaking from such tanks seeps into the ground and is, therefore, dificult to trace back to its point of origin, particularly when several tanks are grouped together in one storage facility.

The leakage of gasoline and other flammable fuels poses a fire threat, and thus it is necessary to determine quickly and accurately which of the tanks is faulty so that immediate repairs can be made.

It is therefore a primary object of this invention to provide a convenient, reliable, and inexpensive method for identifying or determining the origin of seepage gasoline or other liquid, hydrocarbon fuel. it is a further object to provide such a method that does not interfere with normal operation of the storage facility or with the desired performance qualities of the fuel.

In accordance with this purpose, the present invention provides a' process for identifying a liquid, hydrocarbon fuel which comprises adding to the fuel a quantity of thiophane insufficient to affect the odor of the resulting fuel-thiophane mixture but sufficient to produce a detectable, thiophane odor when a sample of the thiophane-fuel mixture is subjected to a physical separation process.

it is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory but are not restrictive of the invention.

The present invention can be used to identify or trace the origin of a variety of liquid, hydrocarbon fuels including gasoline, kerosene, and medium heating oils.

In accordance with this invention, a small amount of thiophane is added to a quantity of the liquid fuel stored in, or to be stored in, a receptacle susceptible to leakage. The amount of thiophane added to the liquid fuel is capable of producing a latent odor. In other words, the amount of thiophane added is insufficient to produce a noticeable change in the odor of the fuel, which possesses its own characteristic odor. Sufficient thiophane is added, however, to allow detection by the characteristic thiophane odor when a sample of the thiophane-containing fuel is subjected to a physical separation process, such as gas chromatography.

The amount of thiophane added to the gasoline is very small invention.

. EXAMPLE To ascertain the origin of seepage gasoline in a tank farm containing several large gasoline storage tanks, 0.1 percent by volume of thiophane is added to the gasoline in the tank located nearest the area of seepage.

After a time sufficient to allow for seepage of the thiophane containing gasoline, a sample of the seepage is taken and separated by passing the sample through a Perkin Elmer 154 gas chromatographic unit having a column length of 6 ft. and containing didecyl phthalate on Chromosorb. With the unit operating at C. and with helium as the carrier gas at 20 p.s.i.g., and a flow rate of 75 cc./min., the thiophane elutes from the sample in about fifteen minutes. Its presence (an intense gassy odor) is easily detected by sniffing the exit gas at this time.

Although the seepage sample exhibited no thiophane odor, the effluent gas from the gas chromatograph column exhibits the characteristic odor of thiophane, thus confirming the existence of a leak in the tank tested.

if no thiophane is detected in the sample, additional samples are taken and analyzed for odor to insure against the possibility of a slow leak. If the results of these subsequent tests are negative and other tanks are suspected of leaking, similar quantities of thiophane are added to these tanks in sequence and the sampling and analysis procedure repeated.

The process of this invention thus provides a quick, convenient, and reliable method for determining the origin of seepage gasoline. This process can be performed in the field by relatively inexperienced persons. Because a wide range of nondeleterious and still detectable concentrations of thiophane can be used, accurate control of the amount of thiophane added to the gasoline is not required. Further, the separation procedures and the identification by odor can be conveniently carried outin any facility that possesses the necessary physical separation equipment.

Thiophane is commercially available for use as a warning odorant in natural gas and other odorless gases to impart an odor to the gases. This commercially available thiophane is suitable for use in the process of this invention.

This invention in its broader aspects is not limited to the specific procedures shown and described, but also includes any departures made from such procedures that do not depart from the principles of the invention and that do not sacrifice its chief advantages.

What is claimed is:

l. A process for determining the origin of the seepage of gasoline comprising:

a. adding to the fuel in a receptacle suspected of seepageja quantity of thiophane insufficient to cause the odor of the resulting gasoline thiophane mixture to differ detectably from the original odor of the gasoline, but sufficient to produce a detectable thiophane odor when the thiophane elutes after a sample of the thiophane-gasoline mixture is passed through a chromatography separation unit, said quantity being 0.05 to 1.0 percent by volume of said gasoline; v

. waiting a period sufficient to allow seepage to occur from the suspected receptacle and then securing a sample of the seepage gasoline; and

. physically separating the components of the seepage sample in a gas chromatography separation unit to concentrate any thiophane present therein and thereby detect the presence of any thiophane in the seepage sample by a thiophane odor. 

